1. Field of Invention
This invention relates generally to door hardware, and more specifically to knockdown apparatus for supporting or suspending a door or doors from above and for driving them between closed and opened positions.
2. Prior Art
Conventional apparatus for supporting and driving overhung doors of the class and kind herein under consideration has been more or less of unitary construction, such that a motor, speed reducer, drive and idler pulleys, rail and so forth are mounted in predetermined relative positions on a common support structure. This support structure is intended to be installed on a transom or the like of a desired doorframe to suspend doors therefrom. Since the longitudinal dimension of such conventional apparatus is predetermined, however, it can be installed on a doorframe of a specified horizontal length only and is not adaptable for use on doorframes of other than the specified length.
Another objection to the noted conventional apparatus relates to its great bulk and weight, which also results from the unified arrangement of all its components. A considerable number of workers must cooperate for installation of the apparatus in an elevated position on a doorframe with the aid of such insecure footings as stools or ladders. Moreover, in the event of trouble in some part of the apparatus, the entire apparatus may have to be removed for repair or readjustment, no matter how minor the trouble may be.